A major goal in the pharmacological arts has been the development of methods and compositions to facilitate the specific delivery of therapeutic and other agents to the appropriate cells and tissues that would benefit from such treatment, and the avoidance of the general physiological effects of the inappropriate delivery of such agents to other cells or tissues of the body. One common example of the need for such specificity is in the field of antiproliferative agent therapy for the treatment of skin diseases and disorders, in which the amount of a variety of antiproliferative agents to be safely administered topically or locally to a patient is limited by their systemic cytotoxic effects.
In addition, it is recognized in the medical arts that certain subcellular organelles are the sites of pharmacological action of certain drugs or are involved in the biological response to certain stimuli. Specific delivery of diagnostic or therapeutic compounds to such intracellular organelles is thus desirable to increase the specificity and effectiveness of such clinical diagnostic or therapeutic techniques. The invention provides polar lipid drug conjugates that target dermal, intradermal and infradermal structures in skin for delivery of therapeutic agents for the treatment of skin diseases and disorders.
Drug Targeting
It is desirable to increase the efficiency and specificity of administration of a therapeutic agent to the cells of the relevant tissues in a variety of pathological states. This is particularly important as relates to antiproliferative agents. Such agents typically have pleiotropic antibiotic and cytotoxic effects that damage or destroy uninvolved cells and tissues as well as cells and tissues comprising the pathological site. Thus, an efficient delivery system which would enable the delivery of such drugs specifically to the diseased or affected tissues cells would increase the efficacy of treatment and reduce the associated xe2x80x9cside effectsxe2x80x9d of such drug treatments, and also serve to reduce morbidity and mortality associated with clinical administration of such drugs.
Numerous methods for enhancing the biological activity and the specificity of drug action have been proposed or attempted. To date, however, efficient or specific drug delivery remains to be predictably achieved.
An additional challenge in designing an appropriate drug delivery scheme is to include within the drug conjugate a functionality which could either accelerate or reduce the rate at which the drug is released upon arrival at the desired site. Such a functionality would be especially valuable if it allowed differential rates of drug release.
Medicinal salves and ointments for topical treatment purposes are known in the prior art for the treatment of a variety of pathological conditions. A multitude of pathological and other conditions have been treated by topical application of many classes of compounds in a variety of carriers, such as salves and ointments. However, carriers used in these conventional treatments are in no way specific for deposition of drugs, and suffer from non-specific deposition of the antiproliferative drug into both healthy and affected portions of the skin. Appropriate concentrations of topically-applied antiproliferative drugs, for example, are currently limited by the escape of the active agent(s) into the systemic circulation, with deleterious effects on other tissues and organs. An example of such a situation is the use of the drug methotrexate to treat psoriasis, where the amount of methotrexate that is capable of being topically applied is limited by hepato- and nephrotoxicity caused by systemic escape of the compound from the skin.
There remains a need in the art for an effective means for delivering biologically-active compounds, specifically drugs including antiproliferative drugs, to skin by topical administration of salves, ointments, and the like. Advantageous embodiments of such delivery means are formulated to efficiently deliver the biologically-active compound to the appropriate layer of the skin, while minimizing transit of the compound into the systemic circulation.
The present invention is directed to an improved method for delivering biologically-active compounds, particularly drugs including preferably antiproliferative, antibiotic, antimycotic, antiviral and antineoplastic drugs, to cells comprising skin in animals in vivo and in vitro. This delivery system achieves specific delivery of such biologically-active compounds through conjugating the compounds with a polar lipid carrier. This invention has the specific advantage of facilitating the entry of such compounds into cells via a polar lipid carrier, achieving effective intracellular concentration of such compounds more efficiently and with more specificity than conventional delivery systems. The invention particularly provides pharmaceutical composition comprising the drug/polar lipid conjugates of the invention formulated with a medicinal ointment or salve for treatment of a variety of skin disorders.
The invention provides compositions of matter comprising a biologically-active compound covalently linked to a polar lipid carrier molecule. Preferred embodiments also comprise a spacer molecule having two linker functional groups, wherein the spacer has a first end and a second end and wherein the lipid is attached to the first end of the spacer through a first linker functional group and the biologically-active compound is attached to the second end of the spacer through a second linker functional group. In preferred embodiments, the biologically-active compound is a drug, most preferably an antiproliferative drug or agent, an antibiotic drug, an antiviral drug, an antineoplastic drug or a corticosteroid. Preferred polar lipids include but are not limited to acyl- and acylated carnitine, sphingosine, ceramide, phosphatidyl choline, phosphatidyl glycerol, phosphatidyl ethanolamine, phosphatidyl inositol, phosphatidyl serine, cardiolipin and phosphatidic acid. Preferred biologically-active compounds include antineoplastic and antiproliferative agents such as methotrexate, corticosteroids, antimycotics, antibiotics and antiviral compounds. Pharmaceutical compositions comprising the drug/polar lipid conjugates of the invention formulated with a medicinal ointment or salve are also provided.
The invention also provides compositions of matter comprising a biologically-active compound covalently linked to a lipid, most preferably a polar lipid, carrier molecule via a spacer molecule wherein the spacer allows the biologically-active compound to act without being released at an intracellular site. In these embodiments of the invention, the first linker functional group attached to the first end of the spacer is characterized as xe2x80x9cstrongxe2x80x9d and the second linker functional group attached to the second end of the spacer is characterized as xe2x80x9cweakxe2x80x9d, with reference to the propensity of the covalent bonds between each end of the spacer molecule to be broken.
In other embodiments of the compositions of matter of the invention, the spacer allows the facilitated hydrolytic release of the biologically-active compound at an intracellular site. Other embodiments of the spacer facilitate the enzymatic release of the biologically-active compound at an intracellular site. In particularly preferred embodiments, the spacer functional group is hydrolyzed by an enzymatic activity found in skin, preferably an esterase and most preferably an esterase having a differential expression and activity profile in different skin layers. In additional preferred embodiments, specific release of biologically-active compounds is achieved by enzymatic or chemical release of the biologically-active compound by intracellular cleavage of a cleavable linker moiety in cells infected by a pathogenic organism or otherwise expressing a disease state (for example, hyperplasia associated with a benign or malignant skin condition) via an enzymatic activity specific for such a pathogenic organism or disease state, or by extracellular cleavage of a cleavable linker moiety via an enzymatic activity specific for a pathogenic organism or disease state.
The invention also provides polar lipid drug conjugates that target dermal, intradermal and infradermal structures in skin for delivery of therapeutic agents for the treatment of skin diseases and disorders. Specifically, the invention provides such conjugates comprising a spacer that allows facilitated hydrolytic or enzymatic release of the biologically-active compound at a dermal, intradermal or infradermal site in skin.
In another embodiment of this aspect of the invention, the spacer molecule is a peptide of formula (amino acid)n, wherein n is an integer between 2 and 25, preferably wherein the peptide comprises a polymer of one or more amino acids.
In other embodiments of the compositions of matter of the invention, the biologically-active compound of the invention has a first functional linker group, and a lipid, most preferably a polar lipid, carrier has a second functional linker group, and the compound is covalently linked directly to the lipid carrier by a chemical bond between the first and second functional linker groups. In preferred embodiments, each of the first and second functional linker groups is a hydroxyl group, a primary or secondary amino group, a phosphate group or substituted derivatives thereof or a carboxylic acid group.
In another aspect of the invention is provided compositions of matter comprising a drug, most preferably an antiproliferative drug, an antineoplastic drug, an antibiotic, an antimycotic, or an antiviral drug, covalently linked to a polar lipid carrier molecule. Preferred embodiments also comprise a spacer molecule having two linker functional groups, wherein the spacer has a first end and a second end and wherein the lipid is attached to the first end of the spacer through a first linker functional group and the drug is attached to the second end of the spacer through a second linker functional group. Preferred embodiments of the invention are provided wherein the drug is an antiproliferative agent, such as methotrexate, an antiviral agent such as an antiherpetic agent, an antibiotic agent such as rifampicin or streptomycin, or an antimycotic such as econazole. Preferred polar lipids include but are not limited to acyl- and acylated carnitine, sphingosine, ceramide, phosphatidyl choline, phosphatidyl glycerol, phosphatidyl ethanolamine, phosphatidyl inositol, phosphatidyl serine, cardiolipin and phosphatidic acid. Pharmaceutical compositions comprising the drug/polar lipid conjugates of the invention formulated with a medicinal ointment or salve are also provided.
The invention also provides compositions of matter comprising an antiproliferative agent, an antineoplastic drug, an antibiotic, an antimycotic, or an antiviral drug, covalently linked to a polar lipid carrier molecule via a spacer molecule, wherein the spacer allows the drug to act without being released at an intracellular site. In these embodiments of the invention, the first linker functional group attached to the first end of the spacer is characterized as xe2x80x9cstrongxe2x80x9d and the second linker functional group attached to the second end of the spacer is characterized as xe2x80x9cweakxe2x80x9d, with reference to the propensity of the covalent bonds between each end of the spacer molecule to be broken.
In other embodiments of the compositions of matter of the invention, the spacer allows the facilitated hydrolytic release of an antiproliferative drug, an antineoplastic drug, an antibiotic, an antimycotic, or an antiviral drug, at an intracellular site. Other embodiments of the spacer facilitate the enzymatic release of the antiproliferative, antineoplastic, antibiotic, antimycotic or antiviral drugs of the invention at an intracellular site. In particularly preferred embodiments, the spacer functional group is hydrolyzed by an enzymatic activity found in skin, preferably an esterase and most preferably an esterase having a differential expression and activity profile in different skin layers. In additional preferred embodiments, specific release of the antiproliferative, antineoplastic, antibiotic, antimycotic or antiviral drugs of the invention is achieved by enzymatic or chemical release of these drugs by intracellular cleavage of a cleavable linker moiety in cells infected by a pathogenic organism or otherwise expressing a disease state (for example, hyperplasia associated with a benign or malignant skin condition) via an enzymatic activity specific for such a pathogenic organism or disease state, or by extracellular cleavage of a cleavable linker moiety via an enzymatic activity specific for a pathogenic organism or disease state.
The invention also provides polar lipid conjugates the antiproliferative, antineoplastic, antibiotic, antimycotic or an antiviral drugs of the invention that target dermal, intradermal and infradermal structures in skin for delivery of therapeutic agents for the treatment of skin diseases and disorders. Specifically, the invention provides such conjugates comprising a spacer that allows facilitated hydrolytic or enzymatic release of the of such antiproliferative, antineoplastic, antibiotic, antimycotic or an antiviral drugs at a dermal, intradermal or infradermal site in skin.
In another embodiment of this aspect of the invention, the spacer molecule is a peptide of formula (amino acid)n, wherein n is an integer between 2 and 25, preferably wherein the peptide comprises a polymer of one or more amino acids.
In still further embodiments of the compositions of matter of the invention are provided an antiproliferative drug, an antineoplastic drug, an antibiotic, an antimycotic, or an antiviral drug, having a first functional linker group, and a polar lipid carrier having a second functional linker group, wherein the drug is covalently linked directly to the polar lipid carrier by a chemical bond between the first and second functional linker groups. In preferred embodiments, each of the first and second functional linker groups is a hydroxyl group, a primary or secondary amino group, a phosphate group or substituted derivatives thereof or a carboxylic acid group. Preferred embodiments of the invention are provided wherein the drug is an antiproliferative agent, such as methotrexate, an antiviral agent such as an antiherpetic agent, an antibiotic agent such as rifampicin or streptomycin, or an antimycotic such as econazole. Preferred polar lipids include but are not limited to acyl- and acylated carnitine, sphingosine, ceramide, phosphatidyl choline, phosphatidyl glycerol, phosphatidyl ethanolamine, phosphatidyl inositol, phosphatidyl serine, cardiolipin and phosphatidic acid. Pharmaceutical compositions comprising the drug/polar lipid conjugates of the invention formulated with a medicinal ointment or salve are also provided.
The invention also provides compositions of matter comprising an antiproliferative drug, an antineoplastic drug, an antibiotic, an antimycotic, or an antiviral drug covalently linked to a polar lipid carrier molecule via a spacer molecule wherein the spacer allows the drug to act without being released at an intracellular site. In these embodiments of the invention, the first linker functional group attached to the first end of the spacer is characterized as xe2x80x9cstrongxe2x80x9d and the second linker functional group attached to the second end of the spacer is characterized as xe2x80x9cweakxe2x80x9d, with reference to the propensity of the covalent bonds between each end of the spacer molecule to be broken.
In other embodiments of the compositions of matter of the invention, the spacer allows the facilitated hydrolytic release of the antiproliferative, antineoplastic, antibiotic, antimycotic or an antiviral drug at an intracellular site. Other embodiments of the spacer facilitate the enzymatic release of a drug as provided by the invention at an intracellular site. In particularly preferred embodiments, the spacer functional group is hydrolyzed by an enzymatic activity found in skin, preferably an esterase and most preferably an esterase having a differential expression and activity profile in different skin layers. In additional preferred embodiments, specific release of the antiproliferative, antineoplastic, antibiotic, antimycotic or antiviral drugs of the invention is achieved by enzymatic or chemical release of these drugs by intracellular cleavage of a cleavable linker moiety in cells infected by a pathogenic organism or otherwise expressing a disease state (for example, hyperplasia associated with a benign or malignant skin condition) via an enzymatic activity specific for such a pathogenic organism or disease state, or by extracellular cleavage of a cleavable linker moiety via an enzymatic activity specific for a pathogenic organism or disease state.
In other embodiments of the compositions of matter of the invention, the spacer allows the facilitated enzymatic or hydrolytic release of the antiproliferative, antineoplastic, antibiotic, antimycotic or an antiviral drug at dermal, intradermal and infradermal structures in skin for delivery of therapeutic agents for the treatment of skin diseases and disorders.
In another embodiment of this aspect of the invention, the spacer molecule is a peptide of formula (amino acid)n, wherein n is an integer between 2 and 25, preferably wherein the peptide comprises a polymer of one or more amino acids.
Preferred embodiments of this aspect of the invention include compositions of matter that are N-methotrexate ceramide, methotrexate-glycylglycylglycylglycyl (SEQ ID No: 1) ceramide ester, methotrexate-(tri-xcex2-hydroxypropionylester)-Ox-ceramide ester, methotrexate-glycylglycylglycylglycyl (SEQ ID No: 1) ceramide ester, methotrexate-aminohexanoyl sphingosine amide, methotrexate-valinylvalinyl sphingosine amide and methotrexate-Ox-ceramide ester.
Particular preferred embodiments of the polar lipid/drug conjugates of this invention are provided as salves and other topically or locally applied compositions comprising the drug/polar lipid conjugates of the invention and any of a variety of emollients or other commonly encountered components of cremes, salves, poultices, lotions, gels or other substances well-known in the art for applying compounds to skin and other tissues. Appropriate formulations of such compositions comprising the drug/polar lipid conjugates of the invention will be apparent and within the skill of one of ordinary skill in this art to advantageously prepare in view of the instant disclosure.
In preferred embodiments, the drug/lipid conjugates of the invention comprise a functionality recognized by an enzymatic activity, most preferably an esterase activity, that has a differential pattern of expression or activity in different skin layers. In additional preferred embodiments, specific release of the antiproliferative, antineoplastic, antibiotic, antimycotic or antiviral drugs of the invention is achieved by enzymatic or chemical release of these drugs by intracellular cleavage of a cleavable linker moiety in cells infected by a pathogenic organism or otherwise expressing a disease state (for example, hyperplasia associated with a benign or malignant skin condition) via an enzymatic activity specific for such a pathogenic organism or disease state, or by extracellular cleavage of a cleavable linker moiety via an enzymatic activity specific for a pathogenic organism or disease state.
As disclosed herein, the invention comprehends a polar lipid-drug conjugate wherein the polar lipid will selectively associate with certain biological membranes, and thereby facilitate entry of the drug into cells and cellular organelles. In embodiments comprising a spacer moiety, the spacer component of the conjugates of the invention will preferably act to release the drug from the lipid, target the conjugate to the cell, or perform other functions to maximize the effectiveness of the drug.
This type of conjugate has numerous advantages. First, the drug-lipid conjugates of the invention promote the intracellular entry of a variety of potentially useful drugs at pharmokinetic rates not currently attainable. Second, the range of targeted cell types is not limited per se by particular, limited biological properties of the cell (such as the number and type of specific receptor molecules expressed on the cell surface). Third, in contrast to traditional attempts to simply target drugs to specific cells, this method may target drugs to specific intracellular organelles and other intracellular compartments. Fourth, the compositions of matter of the invention incorporate a variable spacer region that may allow pharmacologically-relevant rates of drug release from polar lipid carrier molecules to be engineered into the compositions of the invention, thereby increasing their clinical efficacy and usefulness. Thus, time-dependent drug release and specific drug release in cells expressing the appropriate degradative enzymes are a unique possibility using the drug-lipid conjugates of the invention. Fifth, the conjugates of the invention can be combined with other drug delivery approaches to further increase specificity and to take advantage of useful advances in the art. Sixth, the conjugates of the invention can be topically applied to skin, and the layer of skin penetrated determined by the formulation used. Seventh, in such formulations, the amount and activity of the topically-applied drug can be modulated by release via cleavage, preferably hydrolytic cleavage, of the spacer moiety, most preferably by an enzymatic activity in skin that has a differential pattern of expression or activity in different skin layers.
Specific preferred embodiments of the present invention will become evident from the following more detailed description of certain preferred embodiments and the claims.